I was thinking of writing a self-deprecating reply along the lines of "none of my photos are good enough to warrant stealing anyway" but thinking about it, quite a lot of stock photos that get used for various reasons aren't necessarily that good, they just happen to fulfill the purpose.
I've had a lot of my photos on my Pbase site for nearly 10 years now and to my knowledge, none of them have been taken and used by anyone. To me, the advantages inherent in sharing them outweigh the potential disadvantages. None of them are watermarked or registered. If I were a pro, I'd possibly be looking at this differently.